Heated tobacco product use in early pregnancy may increase risk of placental abruption: Study

A new study published in the Journal of Epidemiology and Global Health showed that the risk of placental abruption (PA) was considerably elevated when mothers used heated tobacco products (HTPs) during the first trimester.

When the placenta separates from the uterine wall during pregnancy or before labor is finished, it is known as placental abruption, a serious obstetric problem. For both the mother and the newborn, this condition raises mortality and the risk of serious complications. Maternal smoking has been determined to be the main risk factor among a number of variables influencing the occurrence of PA.

The usage of heated tobacco products has grown in recent years. Electronic devices called HTPs heat tobacco leaves to produce aerosols. Due to the rarity of PA occurrence and the low frequency of smoking among pregnant women, the relationship between exposure to HTP aerosols and PA is still not well understood. Thus, Hikaru Ooba and colleagues examined whether pregnant women who take HTPs are more likely to develop PA than those who do not.

This research examined data from the Japan COVID-19 and Society Internet Survey for their investigation. Surveys were dispersed at random from July 28, 2021, to August 30, 2021. In 2021, respondents who were pregnant were asked to fill out a follow-up survey between February 14 and February 28, 2022.

The results are the relative risk ratio (rRR) and absolute risk difference (aRD) of PA incidence brought on by smoking HTPs during the first trimester of pregnancy. There were 12,836 individuals in the sample size. Inverse probability of treatment weighting (IPTW) and a generalized linear model (GLM) were used to compute the results. Sensitivity analysis was also conducted using the Bayesian technique and multiple-bias analysis.

The researchers discovered a strong rRR of 11.3 (95% CI: 7.5, 17.0) and a robust aRD of 0.07. Incalculable confounders would have to have at least a rRR = 14 link with both exposure and outcome, according to multiple bias analyses, in order to refute the observed correlation.

Neither post hoc analysis nor secondary data usage have occurred. Overall, there was a correlation between smoking HTPs in the early stages of pregnancy and a higher risk of PA. Quantitative data on the possible extent of bias resulting from unmeasured confounding factors was made available via bias analysis.

Reference:

Ooba, H., Maki, J., Tabuchi, T., & Masuyama, H. (2025). Relationship between heated tobacco products and placental abruption: A prospective cohort study using online questionnaire. Journal of Epidemiology and Global Health, 15(1). https://doi.org/10.1007/s44197-025-00373-2